The present invention relates to strings of lights and, in particular, to special application lights used in strings of lights, such as fuse lights and flicker lights. In the present specification, the word light will be used to denote the combination of a bulb, bulb base (or simply “base”), and socket.
Light strings such as the type used to decorate Christmas trees may include sets of 50 or 100 miniature lights arranged electrically in series. In addition to standard lights used in these sets, which meet industry standards set by Underwriters Laboratories (UL Standard 588, in particular), manufacturers have created lights that serve special functions, such as flicker or twinkle lights and fuse lights. While in some cases these special application bulbs may be used in any socket in the light string and in any number, in other cases, the manufacturer may want to limit the number of these special application lights in the string, use them only in special sockets, and even to confine them to specific locations. Under these types of circumstances, the manufacturer may have to anticipate that consumers might inadvertently or through ignorance attempt to place bulbs in the wrong sockets of the light string, and, accordingly, incorporate features into their light string designs to prevent these actions.
One way for manufacturers to achieve this goal of limiting the number and the location of these special application lights in a light string is to make them non-removable from their sockets. However, a determined user, with sufficient effort, can sometimes remove so-called non-removable bulbs. However, this determined consumer may then be confronted by a pair of bare, live wires.
Another way to limit the location and type of special application lights in a light string is to make special application sockets only receive the special application bulb or make special application sockets so that, although they will receive standard bulbs, only special application bulbs will be operable. In addition, manufacturers in some cases will also design special application bulbs so that they will not work in standard sockets.
Another, different, problem facing manufacturers and users of conventional light strings, is that the bulbs can be twisted within their sockets, that is, rotated about their long axis with respect to the sockets. In a conventional set, when a conventional bulb is twisted enough, it will fail. When one light in a conventional series circuit fails, a shunt in the light will enable the socket to pass the electrical current through to the next light so the balance of the light string continues to function. However, the current being carried by remaining lights in the string will be incrementally higher, and the light incrementally brighter, than before. Pranksters have been known to twist one bulb after another in a light string, with the remaining lights getting progressively brighter, until the whole light string fails. This form of amusement creates a dangerous fire hazard.
There remains a need for better lights and better special application lights in particular.